III-Nitride optoelectronic device

ABSTRACT

A p-i-n structure for use in photo laser diodes is disclosed, being formed of an Ga x In 1-x N/GaN alloy (X=0→1). In the method of the subject invention, buffer layers of GaN are grown on a substrate and then doped. The active, confinement and confinement layers of p-type material are next grown and doped, if desired. The structure is masked and etched as required to expose a surface which is annealed. A p-type surface contact is formed on this annealed surface so as to be of sufficiently low resistance as to provide good quality performance for use in a device.

[0001] This invention is made with government support under Contract No.BMDO/ONR-N-00014-93-1-0235, DARPA/ONR-N-00014-95-1-0983 and DARPA/ONRContract No. N00014-96-1-0714. The government has certain rights in theinvention.

FIELD OF THE INVENTION

[0002] This invention relates to semiconductor III-V alloy compounds, aswell as to a method of making III-V alloy compounds for use in diodelasers.

BACKGROUND OF THE INVENTION

[0003] The importance of semiconductor emitters and detectors is rapidlyincreasing along with progress in the opto-electronic field, such asoptical fiber communication, optical data processing, storage and solidstate laser pumping.

[0004] GaN-based compounds are the most promising material system forhigh performance and economical ultraviolet (UV) emittersphotodetectors. With a bandgap energy from 3.4 eV to 6.2 eV, UVphotodetectors with cut-off wavelengths from 200 nm (AIN) to 365 nm(GaN) can be fabricated from this alloy system. The direct bandgap ofAl_(x)Ga_(1-x) N-based detectors are also expected to have betterintrinsic solar blindness than any other UV photodetectors. This makesthem ideal for many applications, such as the surveillance andrecognition of spacecraft, space-to-space communications, the monitoringof welding, as well as engines, combustion chambers, and astronomicalphysics.

[0005] Further, GaN, InN AIN and their alloys (III-Nitrides) have directbandgap energies from 1.9 eV (659 mn) to 6.2 eV (200 mn, which coveralmost the whole visible down to mid-ultraviolet wavelength range.Therefore, one of the most important applications of these materials isto make visible and ultraviolet light-emitting diodes (LED) and laserdiodes (LD) with high quantum efficiency, which are immediately neededin the current commercial markets and can be best achieved by thesematerials.

[0006] The performance of photoconductors and simple p-n junctionphotodiodes can be very limited in terms of speed, responsivity andnoise performance. The optimization of GaN-based UV photoconductorsrequires sophisticated structures such as p-i-n layered structures,heterostructures or even quantum wells.

[0007] To fabricate these structures and achieve high-performancephotodetectors, two critical issues need to be addressed. One is thehigh resistance of the p-type layer and its contact, which introducesignal voltage drop and excess noise at the contact point. The otherproblem is introduced by the p-type layer annealing procedure. The bestway to illustrate these two problems is to describe their effect on theperformances of current blue laser diodes.

[0008] Currently, the demonstrated blue laser diodes are notsignificantly practical since they have to be operated either in pulsedmode or CW at low temperature. In addition, their lifetime is short. Atypical reported blue laser diode structure is a p-n structure with ap-type layer on top. Because of the high resistance of the p-type layerand its contact, excess heating at high current densities is generated,which leads to the failure of the device. Other problems exist as aresult of the growing procedure, which are as follows: First, n-typelayers are grown, followed by InGaN MQW; Mg-doped layers are then grown.Finally, thermal annealing at about 700° C. or low-energy electron beamirradiation (LEEBI) is performed to convert the top GaN:Mg to p-type.Both of these procedures will deteriorate the quality of the bottomlayers, including the promotion of defect and impurity propagation,interface deterioration and, worse than that, the dissociation of theInGaN active layer and interface quality of the InGaNmulti-quantum-well, since InGaN begins to dissociate at temperaturesabove 500° C.

[0009] With regard to emitters, In-Nitride based LEDs have been recentlysuccessfully developed and commercialized, providing coverage fromyellow to blue. Further, blue laser diodes are known in pulsed mode atroom temperature and continuous mode at about 40° C. Blue orshort-wavelength laser diodes are in demand primarily because of theirimmediate need in optical storage and full color flat-panel display. Theoptical storage density is inversely proportional to the square of thewavelength of the read-write laser diode. By simply replacing thecurrently used laser diode (780 nm) with blue laser diode (410 nm), thestorage density can be enhanced by almost four times.

SUMMARY OF THE INVENTION

[0010] An object, therefore, of the invention is a DI-Nitride alloy foruse in photoconductors and diodes having high quantum efficiency.

[0011] A further object of the subject invention is a GaN-based MQWcomposition in a p-i-n structure of high quality.

[0012] A still further object of the subject invention is an alloy ofthe composition GaN/Ga_(x)In_(1-x)N in a standard p-i-n structure.

[0013] Those and other objects are attained by the subject inventionwherein a GaN/Ga_(x)In_(1-x)N alloy (X=0→1) is grown by MOCVD procedurein a p-n structure (no aluminum need be present, if desired) with the nor p-type layer adjacent the substrate. In the method of the subjectinvention, buffer layers of n-type material are grown on a substrate.The active layers, and confinement layers of p-type material are nextgrown. The structure is masked and etched as required to expose asurface. An n-type surface contact is formed on this exposed surface,and a p-type surface contact is formed on the masked areas, to providegood quality device performance.

DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1(a) is a cross-section of a GaN based diode structureaccording to the subject invention.

[0015]FIG. 1(b) is a cross-section of the structure of FIG. 1(a) afterprocessing.

[0016]FIG. 2(a) is a graph showing room temperature photoluminescence ofthe structure of FIG. 1(b).

[0017]FIG. 2(b) is a description of optical pumping and stimulatedemission from the structure of FIG. 1(b).

[0018]FIG. 3 is a graph showing the spectrum for the structure of FIG.1(b).

[0019]FIG. 4 is a graph showing the 79° K. electroluminescense spectrumfor a GaInN/GaN MQW.

[0020]FIG. 5 is a graph of the output power vs. injection current for aMQW GaInN/GaN 405 nm uncoated diode laser at 79° K.

[0021]FIG. 6 is a graph of thresh hold current density vs. inversecavity length for 100 μm wide GaInN/GaN MQW lasers at 75° K.

[0022]FIG. 7 is a graph of output power vs. injection current for a MQWGaInN/GaN uncoated diode at 300° K.

[0023]FIG. 8 is a graph showing the temperature dependence of thethreshold current density of the laser of FIG. 7.

[0024] FIGS. 9(a) and 9(b) are graphs showing far field spectra for thedevice of the subject invention.

DETAILED DESCRIPTION OF THE INVENTION

[0025] The reactor and associated gas-distribution scheme used hereinare substantially as described in U.S. Pat. No. 5,384,151. The systemcomprises a cooled quartz reaction tube pumped by a high-capacityroughing pump (120 hr⁻¹) to a vacuum between 7 and 760 Torr. Thesubstrate was mounted on a pyrolytically coated graphite susceptor thatwas heated by rf induction. The pressure inside the reactor was measuredby a mechanical gauge and the temperature by an infrared pyrometer. Amolecular sieve was used to impede oil back-diffusion at the input ofthe pump. The working pressure was adjusted by varying the flow rate ofthe pump by using a control gate valve. The gas panel was classical,using ¼-inch stainless steel tubes. Flow rates were controlled by massflow control.

[0026] The reactor was purged with a hydrogen flow of 4 liters min⁻¹,and the working pressure of 10-100 Torr was established by opening thegate valve that separated the pump and the reactor. The evacuation linethat was used at atmospheric pressure was automatically closed by theopening of the gate valve. The gas flow rates were measured understandard conditions, i.e., 1 atm and 20° C., even when the reactor wasat subatmospheric pressure.

[0027] The gas sources used in this study for the growth of GaN andGaInN by LP-MOCVD are listed below. Group-III Sources Group-V Source Al(CH₃)₃ t-butylamine Al (C₂H₅)₃ NH₃ In(CH₃)₃ In(C₂H₅)₃ (CH₃)₂In(C₂H₅)Ga(CH₃)₃ Ga(C₂H₃)₃

[0028] An accurately metered flow of purified H₂ or N₂ for TMI is passedthrough the appropriate bubbler. To ensure that the source materialremains in vapor form, the saturated vapor that emerges from the bottleis immediately diluted by a flow of hydrogen or N₂. The mole fraction,and thus the partial pressure, of the source species is lower in themixture and is prevented from condensing in the stainless steel pipework. If necessary the active buffer and confinement layers may beprepared without the presence of aluminum.

[0029] Pure and diluted ammonia (NH₃) is used as a source of N. Themetal alkyl or hydride flow can be either injected into the reactor orinto the waste line by using two-way valves. In each case, the sourceflow is first switched into the waste line to establish the flow rateand then switched into the reactor. The total gas flow rate is about 8liters min⁻¹ during growth. Stable flows are achieved by the use of massflow controllers.

[0030] Dopants usable in the method of the subject invention are asfollows: n dopant p dopant H₂Se (CH₃)₂Zn H₂S (C₂H₅)₂ Zn (CH₃)₃Sn (C₂H₅)₂Be (C₂H₅)₃Sn (CH₃)₂Cd SiH₄ (ηC₂H₅)₂Mg Si₂H₆ Cp₂Mg GeH₄

[0031] Co-doping, i.e., doping with two or more dopants of like type,may be conducted.

[0032] The substrate can be GaAs, Si, Al₂O₃, MgO, SiC, ZnO, LiGaO₂,LiAlO₂, MgAl₂O₄ or GaN. Preferably, sapphire (Al₂O₃) is used as thesubstrate. The epitaxial layer quality is sensitive to the pretreatmentof the substrate and the alloy composition. Pretreatment of thesubstrates prior to epitaxial growth was thus found to be beneficial.One such pretreatment procedure is as follows:

[0033] 1. Dipping in H₂SO₄ for 3 minutes with ultrasonic agitation;

[0034] 2. Rinsing in Deionized H2O;

[0035] 3. Rinsing in hot methanol;

[0036] 4. Dipping in 3% Br in methanol at room temperature for 3 minutes(ultrasonic bath);

[0037] 5. Rinsing in hot methanol;

[0038] 6. Dipping in H₂SO₄ for 3 minutes;

[0039] 7. Rinsing in deionized H₂O, and

[0040] 8. Rinsing in hot methanol.

[0041] After this treatment, it is possible to preserve the substratefor one or two weeks without repeating this treatment prior to growth.

[0042] The invention is described in accordance with the drawings and,in particular, with respect to FIG. 1.

[0043] Growth takes place by introducing metered amounts of thegroup-III alkyls and the group-V hydrides into a quartz reaction tubecontaining a substrate placed on an rf-heated susceptor surface. The hotsusceptor has a catalytic effect on the decomposition of the gaseousproducts; the growth rate is proportional to the flow rate of thegroup-III species, but is relatively independent of temperature between700° and 1000° C. and of the partial pressure of group-V species aswell. The gas molecules diffuse across the boundary layer to thesubstrate surface, where the metal alkyls and hydrides decompose toproduce the group-III and group-V elemental species. The elementalspecies move on the hot surface until they find an available latticesite, where growth then occurs.

[0044] High quality GaN/GaInN may be grown in the method of the subjectinvention by low pressure metalorganic chemical vapor deposition(LP-MOCVD). Other forms of deposition of III-V is such as the subjectinvention, may be used as well including MBE (molecular beam epitaxy),MOMBE (metalorganic molecular beam epitaxy), LPE (liquid phase epitaxyand VPE (vapor phase epitaxy).

[0045] For best results, all surfaces of the growth reaction chamber arecoated with a barrier coating capable of withstanding high temperaturesand not reacting with the reactants and dopants utilized therein at suchhigh temperatures. Preferably, a coating of AIN or of SiC is grown insitu in the reaction chamber to cover all surfaces therein. There isthus formed a stable layer that prevents oxygen and other impuritiesoriginating within the reaction chamber from reacting with thesemiconducting layer to be grown.

[0046] High quality GaInN may be grown in the method of the subjectinvention by low pressure metallorganic chemical vapor deposition(LP-MOCVD). The layers of the heterostructure are grown by aninduction-heated horizontal cool wall reactor. Trimethylindium (TMI),and Triethylgallium (TEG) are typically used as the sources of Indiumand Gallium. Pure and diluted ammonia gas (NH3) is used as the N source.Sample is typically grown on a sapphire substrate. A buffer layer of GaNand thin contact and confinement layers of GaN, and G_(x)In_(1-x)N(X=0→1) are individually laid on the substrate at thicknesses from 50 Åto a few μm. The undoped active layer may be In_(x)Ga_(1-x)N (0≦X≦1),preferably (0.01≦x≦0.99) or the superlattice structure ofGaN/Ga_(x)In_(1-x)N (0≦X≦1), preferably (0.01≦x≦0.99). The optimumgrowth conditions for the respective layers are listed in Table 1. Theconfinement of the active layer for the subject invention may be as aheterostructure, separate confinement heterostructures or with a quantumwell.

[0047] Doping is preferably conducted with bis-cyclopentadienylmagnesium (CP₂Mg) for p-type doping and silane (SiH₄) for n-type doping.Doping is performed through a BCP₂Mg bubbler with H₂ as carrier gas andat temperatures from −15° C. to ambient temperatures at 20-1500 cm³min.⁻¹ and onto either a hot or cooled substrate. Dilute SiH₄ may besimply directed at ambient temperatures onto the hot substrate at 20-90cm³ min.⁻¹.

[0048] In a preferred doping method for incorporating the maximum amountof p-type dopant on the layer, once the p-type layer to be doped isfully grown, the heat source is terminated and the substrate allowed tocool; the metal and hydride sources are terminated; the dopant flow, forinstance DEMg, is initiated at the temperatures indicated for diffusiononto the cooled substrate/epilayer which has been previously grown.After about 2-3 minutes, the dopant flow is terminated and the nextepilayer grown. By this method, it is found that 10²⁰ atoms/cm³ of Mgmay be placed on the top surface of the epilayer. TABLE 1 Optimum growthconditions of a Ga_(x)In_(1−x)N/GaN structure. GaInN GaN Growth Pressure76 76 Growth Temperature ˜800 ˜1000 (C) Total H₂ Flow 3 3 (liter/min)TMI (cc/min) 200 — TEG (cc/min) 120 120 NH₃ (cc/min) ˜3000 ˜3000 GrowthRate 30 250 (Å/min)

EXAMPLE

[0049] The epitaxial layers are grown on (0001) sapphire substratesusing a horizontal flow low pressure metalorganic chemical vapordeposition (LP-MOCVD) reactor. The inductively heated SiC-coatedgraphite susceptor is rotated at a speed of ˜50-100 rpm to achievebetter uniformity films. Trimethyl-gallium (TMGa) and triethyl-gallium(TEGa) are used as the gallium (Ga) source materials, trimethyl-indium(TMIn) is used as the indium (la) source and purified ammonia (NH3) isused as the nitrogen (N) source. Bis-cyclopentadienyl-magnesium (Cp₂Mg)and silane (SiH₄) are used as the magnesium (Mg) and silicon (Si) dopingsource materials respectively. The carrier gases include Palladiumdiffused hydrogen and resin purified nitrogen.

[0050] The device structure is shown in FIG. 1(a). First, a thin(20-4000 Å and preferably ˜200 Å) GaN buffer is grown at low temperature(500-600° C.) on the sapphire substrate. Then, a 3 μm-thick Si-doped GaNlayer is grown at ˜1000° C. at a growth rate of 1.5 μm/hr using TMGa,NH₃, SiH₄ and hydrogen as the carrier gas. This layer typically exhibitsa room temperature free electron concentration of 2×10¹⁸ cm⁻³ andmobility of 300 cm²/Vs. The growth temperature was then cooled down to˜750° C., while growing Si-doped or undoped GaN and the carrier gas isswitched from hydrogen to purified nitrogen. A 10 or 20 period multiplequantum well (graded-index multiple quantum wellheterostructure-GRINSCH) structure is then grown using TEGa, TMIn andNH₃ with a growth of 0.2 μm/hr. Each period consists of Si-doped orundoped 33 Å Ga_(0.89)In_(0.11)N/66 Å GaN. Then, the growth temperatureis increased to 1000° C., while growing Mg-doped GaN and while hydrogenis being re-introduced into the reaction chamber. Finally, a 0.25μm-thick Mg-doped GaN layer is grown using TMGa, Cp₂Mg and NH₃ at agrowth rate of 1.5 μm/hr. The sample was then slowly cooled down toavoid formation of cracks. The laser structures here are different fromany other reported III-Nitride based laser structure because it does notinclude any AlGaN cladding layer, although a AIGaN clodding layer may beused.

[0051] After epitaxial growth, the wafers are annealed using rapidthermal annealing (RTA) under nitrogen ambient for 30 seconds at 1000°C. to achieve low resistivity p-type GaN:Mg. Typically, the roomtemperature free hole concentration is 2×10¹⁷ cm⁻³ and mobility is 10cm²/Vs. Ni/Au metal contacts are deposited on the p-type GaN using anelectron-beam evaporator. 10 to 100-μm wide stripes are defined byconventional photolithography and are fabricated using ECR-RF dryetching using a SiCl₄/Ar chemistry. The structure is partially etcheduntil the underlying n-type GaN:Si layer is exposed, as shown in FIG.1(b). Ti/Au metal contacts are then deposited on the n-type GaN using anelectron-beam evaporator. The metal contacts are defined by aconventional lift-off process known in the art.

[0052] Mirror facets for laser diodes are mechanically polished toachieve various cavity lengths from 700 μm to 1800 μm. The roughness ofthe facet surface is in the range of 50 nm. No antireflection orhigh-reflection coatings are applied on the mirror facets. The laserdiodes are bonded with indium to copper heatsinks and are tested underpulse and continuous wave operation between 79° and 325° K.

[0053] Material Characterization

[0054]FIG. 2 shows the room temperature photoluminescence Peak A andoptical pumping Peak B from a 10 period 33 Å Ga_(0.89)In_(0.11)N/66 ÅGaN MQW structure capped with only a thin (˜500 Å) undoped GaN layer.The photoluminescence measurements are conducted using a 10 mWcontinuous wave He-Cd laser (325 nm). The optical pumping is carried outusing a pulsed nitrogen laser (337 nm) with a pulse width of 600 ps anda repetition rate of 6 Hz. Neutral density filters are used to attenuatethe optical power. Stimulated emission is collected from a bar withmechanically polished edges and is observed for pumping densities higherthan a threshold estimated at 100 kW/cm². The peak position was 401 nmand its width of ˜1 nm is limited by the resolution of the measurementequipment.

[0055]FIG. 3 shows the room temperature electroluminescence spectrumfrom a laser diode for increasing injected currents under continuouswave operation. The light is collected from the substrate side of thesample. An intense electroluminescence peak at ˜416 nm is observed.

[0056] In FIG. 4, Peak (d) shows the 79° K. electroluminescence spectrumof this laser structure, exhibiting a peak at ˜403 nm. Peak (c) showsthe 79° K. photoluminescence of the MQW laser structure. In order to beable to detect photoluminescence from the multi-quantum wells in thelaser structures, the top 0.25 μm p-type GaN:Mg layer is partiallyremoved by dry etching to allow penetration of the laser beam. Thespectrum exhibits a small peak at ˜384 nm and an intense peak at 410 nm.The full width at half maximum of the peak at 410 nm is ˜11 nm. Thiswidth and the presence of two peaks in the spectrum strongly suggeststhat there is some degree of phase separation in the MQW structure,leading to localized regions—e.g. quantum dots—which are In rich andothers regions which are In deficient.

[0057] Laser Diode Testing at 79 K Under Pulse Operation

[0058] Pulse operation light-current characteristics are recorded at arepetition rate 200 Hz and a pulse width of 2-6 μs using a silicondetector. From the current versus voltage (I-V) curve, the seriesresistance of the laser (L˜1800 μm) is estimated to be 13 Ω at 300° K.(turn-on voltage˜3.6 V) and 14 Ω (turn on voltage ˜6V) at 79° K., asshown in FIG. 5. When decreasing the sample temperature from 300° to 79°K., the resistivity of the p-type GaN:Mg is expected to increasedrastically, by at least two orders of magnitude, as a result of therelatively high activation energy of Mg levels in GaN. The fact that theseries resistance does not increase significantly in these diodes may bedirectly due to the small thickness of the GaN:Mg layer, to the absenceof AlGaN cladding layers or to higher p-type doping of GaN:Mg whichresults in lower device resistances.

[0059]FIG. 5 illustrates the light output power versus injection currentof an uncoated 1800 μm-long laser at 79° K. Stimulated emission isobserved at currents of 2.5 A which corresponds to a threshold currentdensity of 1.4 kA/cm². The voltage of this laser at threshold was 25 V.The peak wavelength of the measured lasers is 405 nM at 3.4 A as shownin FIG. 5. At currents lower than 4 A, no degradation is observed forthese diodes under pulse operation. The threshold current density forseveral lasers of different cavity length is measured and the resultsare summarized in FIG. 6.

[0060] Laser Diode Testing at 300° K. Under Pulse and Continuous WaveOperation

[0061] Pulse operation light-current characteristics are recorded atroom temperature at a repetition rate 200 Hz and a pulse width of 5 μsusing a silicon detector. The series resistance of the diodes is 5 Ω.FIG. 7 illustrates the light output power versus injection current of anuncoated 1200 μm-long laser at 300° K. Stimulated emission is observedat currents that correspond to a threshold current density of 300 A/cm².The voltage of this laser at threshold was 5 V. The peak wavelength ofthe measured lasers is 410 nm as shown in FIG. 7.

[0062]FIG. 8 shows the temperature dependence of the threshold currentdensity. A characteristic temperature of 132° K. can be extracted. FIGS.9(a) and 9(b) show the far-field spectra in the perpendicular andparallel directions, respectively, for a 10 μm-wide and 1.6 μm-longlaser at 300° K. under pulse wave operation.

[0063] While the invention has been described with reference to apreferred embodiment, it will be understood by those skilled in the artthat various changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments and equivalents.

1. A multi-quantum well laser diode comprising: a substrate, a bufferlayer, a lower confinement layer, an active layer and an upperconfinement layer; said upper confinement layer being doped with ap-dopant, said lower confinement layer being doped with a n-dopant; andsaid active layer being about 5 to about 30 period GRINSCH structurecomprising a plurality of layers of Ga_(x)In_(1-x)N/GaN (0≦x≦1).
 2. Themulti-quantum well laser diode of claim 1, wherein said buffer layer isGaN.
 3. The multi-quantum well laser diode of claim 2, wherein the GaNbuffer layer is about 20-4000 Å.
 4. The multi-quantum well laser diodeof claim 1, wherein the lower confinement layer is about 3 μm thick. 5.The multi-quantum well laser diode of claim 4, wherein the lowerconfinement layer is GaN.
 6. The multi-quantum well laser diode of claim5, wherein the lower confinement layer is doped with Si, Ge, S, or isco-doped.
 7. The multi-quantum well laser diode of claim 1, wherein theupper confinement layer is about 0.25 μm thick.
 8. The multi-quantumwell laser diode of claim 7, wherein the upper confinement layer isdoped with Mg.
 9. The multi-quantum well laser diode of claim 8, whereinthe upper confinement layer is GaN.
 10. The multi-quantum well laserdiode of claim 1, wherein the active layer is a plurality of successiveGaInN/GaN layers.
 11. The multi-quantum well laser diode of claim 1,wherein the active layers are a plurality of 33 Å GaInN layers, eachsuch layer adjacent to a 66 Å GaN layers.
 12. The multi-quantum welllaser diode of claim 1, wherein the active layer comprises 10-20successive GaInN/GaN layers in a GRINSCH structure.
 13. Themulti-quantum well laser diode of claim 1, wherein there is no Aluminumpresent in the buffer layer, upper confinement layer, lower confinementlayer, and active layer.
 14. The multi-quantum well laser diode of claim1, wherein x=0.89.
 15. A method of forming a multi-quantum well laserdiode comprising the successive steps of: a) growing a buffer layer on acleaned substrate; b) growing a lower confinement layer on the bufferlayer; c) doping the lower confinement layer with a n-type dopant; d)growing an active layer by growing, in sequence, successive layers ofGaInN/GaN. e) repeating step (d) until from about 5 to about 30 layersare formed; f) growing an upper confinement layer on the active layer;g) doping the upper confinement layer with a p-type dopant; annealingand forming contacts on the upper and lower confinement layers
 16. Themethod of claim 15, wherein said buffer layer is GaN.
 17. The method ofclaim 16, wherein the GaN buffer layer is formed to a thickness of about20-4000 Å.
 18. The method of claim 15, wherein the lower confinementlayer is formed to a thickness of about 3 μm thick.
 19. The method ofclaim 18, wherein the lower confinement layer is formed of GaN.
 20. Themethod of claim 19, wherein the lower confinement layer is doped withS₁.
 21. The method of claim 15, wherein the upper confinement layer isformed to a thickness of about 0.25 μm to about 0.8 μm thick.
 22. Themethod of claim 21, wherein the upper confinement layer is doped withMg, Be, Zn, Cd, or is cooped.
 23. The method of claim 22, wherein theupper confinement layer is formed of GaN.
 24. The method of claim 15,including forming the active layers is a GRINSCH structure formed of aplurality of 33 Å GaInN layers, each such layer adjacent to a 66 Å GaInNlayer.
 25. The method of claim 15, wherein the active layer comprises 10successive GaInN/GaN layers.
 26. A multi-quantum well laser diodecomprising: a substrate, a buffer layer of GaN, a lower confinementlayer of GaNi:Si, an active layer and an upper confinement layer ofGaNi:Mg; said active layer being an about 10 to about 20 period multiplequantum well structure comprising a plurality of layers ofGa_(x)In_(1-x)N/GaN (0→1).
 27. The multi-quantum well laser diode ofclaim 26, wherein said Ga_(x)In_(1-x)N/GaN is Ga_(0.89)In_(0.11)N. 28.The multi-quantum well laser diode of claim 27, wherein each layer ofGaInN is 33 Å thick and each layer of GaN is 66 Å thick.
 29. A method offorming a multi-quantum well laser diode comprising the successive stepsof: a) growing a buffer layer of GaN on a cleaned substrate; b) growinga lower confinement layer of GaN: Si on the buffer layer; c) growing anactive layer by growing, in sequence, successive layers ofGa_(x)In_(1-x)N/GaN (1≧x≧0). d) repeating step (d) until from about 10to about 15 layers are formed of Ga_(x)In_(1-x)N/GaN (0→1). e) growingan upper confinement layer of GaNi:Mg on the active layer; f) annealingand forming contacts on the upper and lower confinement layers.
 30. Themethod of claim 29, wherein x=0.89.